A face plate for a cathode ray tube is made by grinding a surface and an edge of a casting produced by pouring gob delivered from a furnace into a mold, pressing and casting the gob.
The quality of the face plate having passed through a grinding process is determined through an inspecting process wherein one checks whether a flaw which may worsen a screen quality exists on the surface of the face plate, whether an alien substance or a bubble is included in the face plate, or whether an unground portion remains on the surface of the plate, or not.
An inspector has no choice but to inspect the surface of the face plate only with his naked eyes, more concretely, the surface inspecting is performed by holding up slantly the face plate as supplied from a conveyor at an angle before a lighting means, and inspecting for a flaw; alien substance or unground part.
This work is quite a difficult one since the inspector has to personally hold up the heavy face plate before the lighting means with his own hands.
The above-mentioned disadvantages can be solved through automatization of the inspecting process.
However, as far as apparatus is not available for detecting a flaw, the alien substance or the unground portion existing in a face plate, it is impossible to automatize the inspecting process, considering the present technical level. Even if it is possible to automatize the inspecting process, any profit is not expected.